Search for UMa group companions

While many extra-solar planets and planetary candidates have been found in close orbits around stars by the radial velocity and the transit methods, direct detections at wider orbits are rare. The UMa group, a young nearby stellar association at an age of about 200-600Myr, has not yet been addressed as a whole although its members represent a very interesting sample to search for and characterize substellar companions by direct imaging.

Our goal was to find or to provide detection limits on wide substellar companions around nearby UMa group members using high-resolution imaging. We searched for faint companions around 20 UMa group members within 30pc. The primaries were placed below a semi-transparent coronagraph, a rarely used mode of NACO, to increase the dynamic range of the images.